The present invention relates to a magnetic closure device, especially for articles of non-magnetic materials, such as leather goods, textiles, synthetic materials, and so forth.
Closure devices of various kinds and useful for non-magnetic articles are known in large numbers. The so-called slide closure devices including various kinds of zippers are to be mentioned in this respect. Further, so-called rotary closure devices are also well known, whereby the latter are mainly used in connection with briefcases and the like.
Tension and pressure responsive closure means capable of taking up larger forces are also well known. Strapping closure devices belong in this group and are preferably used in connection with ski boots. In addition, there are buckle closure devices for belts and shoes. Especially the latter are well known in numerous embodiments.
Most of the known closure devices, especially the zipper type of closures require numerous individual parts which can be closed or opened only by applying more or less force resulting in a respective wear and tear. Another disadvantage of known closure devices is seen in their relatively limited adjustability. Thus, especially briefcase closure devices normally have only one closing position. Another disadvantage of prior art devices is seen in the substantial costs for the manufacturing of a large number of individual parts and assemblying such parts, whereby the production of the individual parts also requires a substantial capital investment for machinery and tools. A further drawback of prior art devices is seen in the fact that they are prone to failure, since it is unavoidable that individual parts may break easily, because due to weight considerations such parts are of a rather light construction. Furthermore, especially those embodiments of the prior art which require a substantial number of links and levers and so forth are also prone to failure, because these links and levers may easily be damaged or bent or even broken.
German patent publication No. 1,760,095 discloses a shoe closure device especially for ski boots, which is provided with a magnetic safety catch. Such a safety catch comprises two interlocking closure members provided with permanent magnets having plane surfaces contacting each other. The pulling or tension forces tending to separate the closure members are taken up solely in a mechanical manner by the steep serrated flanks of the closure members. Practical experience has shown that this type of closure device results in an increased pressure, especially along the edges of the closure device and such pressure is transmitted to the foot or the ankle of the person wearing such boots. Another drawback is seen in that for closing the two closure members a substantial stretching of the boot uppers is necessary to a position extending even beyond the closure position, because the serrated flanks must be relatively large for this purpose. This stretching is especially required where the ski probe or rather its tip is used for the closing. Thus, the shoe uppers may easily be damaged by the ski pole tip and the serrated flanks of the closure members are subject to rapid wear.
U.S. Pat. No. 2,389,298 (Ellis) discloses a magnetic closure device wherein two serrated, permanent magnets are corrugated. Since the magnetic poles are located at the ends of the serrations there is room for improvement, especially since in Ellis the two permanent magnets begin to push away from one another when magnetic poles of equal polarity come to face each other.